Optimization of lovastatin production by Fusarium nectrioides (MH173849) using response surface methodology and fuzzy logic system

ABSTRACT

Aim: To enhance the productivity of lovastatin from Fusarium nectrioides isolate with liquid cheese whey as a major carbon source and to optimize the media components using Response Surface Methodology (RSM) and Fuzzy Logic System (FLS). Methodology: Euphorbia hirta was collected, surface sterilized and incubated on potato dextrose agar medium amended with ampicillin and streptomycin sulphate. F. nectrioides was isolated from E. hirta and identified using morphological and molecular methods. Primarily, media components were screened by Plackett Burman design (PBD). Further, the effect of significant nutrients was predicted using RSM and FLS and compared with experimental yield. Results: Molecular identification by gene sequencing confirmed the isolate to be F. nectrioides, given an accession number (MH173849) the sequence was submitted in the gene bank. PBD revealed that peptonized milk (which is an enzymic digest of high grade skimmed milk powder), corn steep liquor, liquid cheese whey and histidine were significant variables. The optimum levels of these significant variables in different combinations were studied by RSM in which the predicted yield of lovastatin was 1.2 gl-1. Further, it was analyzed by FLS with 14 set of fuzzy rules and the maximum production obtained was 1.8 g100 ml-1 which was closer to the experimental yield of 1.75 g100 ml-1. Therefore, compared to RSM, FLS was more suitable technique to determine the optimum levels of significant nutrients for enhanced lovastatin production. Interpretation: This study suggests that F. nectrioides (MH173849) can be used as a potent producer of lovastatin and the production highly influenced by glucose, corn steep liquor, liquid cheese whey and histidine.